White matter abnormalities of right hemisphere attention networks contribute to visual hallucinations in dementia with Lewy bodies
Cortex. 2021-06-01; 139: 86-98
DOI: 10.1016/j.cortex.2021.03.007
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Zorzi G(1), Thiebaut de Schotten M(2), Manara R(3), Bussè C(4), Corbetta M(5), Cagnin A(3).
Author information:
(1)Department of Neuroscience, University of Padova, Padova, Italy; Padova
Neuroscience Center, University of Padova, Padova, Italy. Electronic address:
.
(2)Padova Neuroscience Center, University of Padova, Padova, Italy; Brain
Connectivity and Behaviour Laboratory, Sorbonne Universities, Paris, France;
Groupe d’Imagerie Neurofonctionnelle, Institut des Maladies
Neurodégénératives-UMR 5293, CNRS, CEA University of Bordeaux, Bordeaux, France.
(3)Department of Neuroscience, University of Padova, Padova, Italy; Padova
Neuroscience Center, University of Padova, Padova, Italy.
(4)Department of Neuroscience, University of Padova, Padova, Italy.
(5)Department of Neuroscience, University of Padova, Padova, Italy; Padova
Neuroscience Center, University of Padova, Padova, Italy; Department of
Neurology, Radiology, Neuroscience, Washington University School of Medicine,
St.Louis, MO, USA.
Objective
Functional alterations of the visual attention networks in a setting of impaired visual information processing have a role in the genesis of visual hallucinations (VH) in dementia with Lewy bodies (DLB). This multimodal MRI study aims at exploring structural and functional basis of VH.
Methods
23 DLB patients (10 with and 13 without VH) and 13 healthy controls were studied. They underwent MRI with T1-w sequences to measure cortical thickness, DTI for whole-brain and single tract microstructural properties and rs-fMRI of the default mode, dorsal and ventral attention, and visual networks.
Results
In DLB with VH, whole-brain DTI revealed a lower fractional anisotropy and a greater mean diffusivity in the right frontal and temporo-parietal white matter tracts. Tracts dissection showed lower fractional anisotropy in the right inferior and superior (ventral part) longitudinal fasciculi (ILF and SLF) (p < .05, corrected), and greater mean diffusivity (p < .05). The extent of white matter microstructural alterations involving the right ILF and SLF correlated with the severity of VH (r = .55, p < .01; r = .42, p < .05, respectively), and with performance in the visual attention task (r = −.56 and r = −.61; p < .01, respectively). Cortical thickness in the projection areas of the right SLF was significantly reduced (p < .05). Patients with VH also showed an altered functional connectivity in the ventral attention network, connected by the ventral portion of the SLF (p < .05).
Conclusions
Our findings suggest that a combination of microstructural and functional alterations involving the attention networks in the right hemisphere may be important in the genesis of VH.